A lancet is an instrument designed to puncture and make a small incision in the skin to obtain a few drops of blood for testing or otherwise. The puncture can be made on any appropriate area, such as a fingertip. In infants and small children, the incision is usually made in the patient's heel. Typically, the lancet includes a disposable blade that is housed within the device prior to use for safety reasons. Upon activation of the device, the blade is biased by a spring out of the housing and into contact with the user's skin with force sufficient to create the incision. After firing, the blade is retracted back into the housing for safety reasons. To prevent the spread of infectious diseases and otherwise maintain the sterility of the device, such lancets are typically single use devices that cannot be rearmed and re-used once fired.
Many different lancet designs are available. According to one exemplary design, a lancet is positioned against the desired incision site and a portion of the housing is pressed against the incision site, which triggers release of the spring and fires the device. With these types of devices, the lancet housing moves relative to the incision site, which increases the tolerance of the device and leads to more variability in the depth and width of the incision.